NURS 611 Advanced Pathophysiology Exam #3 Study Guide
Week 8 The Hematologic System: Chapters 28, 29 & 30
Chief Functions
I. Delivery of substances
... [Show More] needed for cellular metabolism in the tissues (Transports hormones; conveys WBCs, platelets, and other ingredients needed for protection from injury & infection & initiating the healing process)
II. Removal of the wastes of cellular metabolism
III. Defense against microbes & injury
IV. Maintenance of acid-base balance (fluid portion carries nutrients & ions)
Extra functions: RBCS provide O2 and remove CO2, Provides thermal regulation to maintain organs & tissues
Blood Composition: various cells that circulate in the CV system suspended in a solution of protein & inorganic materials (plasma), which is 92% H2O and 8% solutes
* Total of 6 quarts (5.5L)
Plasma & Plasma Proteins- 50-55% blood volume, complex aqueous liquid containing organic & inorganic elements
* Serum refers to plasma that has been allowed to clot in a lab in order to remove fibrinogen and other clotting factors
* Proteins make up 7% of total plasma weight, majority made by the liver with the exception of antibodies (made by plasma cells in the lymph nodes & other lymphoid tissues), classified into two major groups: albumin & globulins
Albumin: most essential role is regulation of the passage of H2O and solutes through the capillaries, maintain the colloidal osmotic pressure
Globulins: classified by their movement relative to albumin: alpha (ones that move most like albumin), beta, and gamma (least movement)
* Fibrinogen, the most plentiful of the clotting factors & is the precursor of the fibrin clot
* Can also be classified into groups by function: clotting, defense, transport or regulation
Cellular Components of Blood: RBCs (erythrocytes), WBCs (leukocytes), and platelets (thrombocytes)
A. Erythrocytes
* Most abundant cells (42-48% of blood)
* Contains hemoglobin (carries gases and electrolytes)
* Small disk with 2 unique properties: Biconcave shape and capacity to be reversibly deformed
B. Leukocytes
* Defend against microbes and remove debris
* Act primarily in the tissues but transported via circulation
* Classified according to structure as either granulocytes (neutrophils, basophils, eosinophils & mast cells) or agranulocytes (monocytes, macrophages, lymphocytes) & according to function as either phagocytes (monocytes & macrophages) or immunocytes (lymphocytes)
C. Platelets (not true cells but irregularly shaped cytoplasmic fragments needed for blood coagulation)
Lymphoid Organs: classified as either primary or secondary
Primary consist of thymus & bone marrow
Secondary consist of the spleen, lymph nodes, tonsils and Peyer patches in the ileum of the small intestine
The Spleen: Largest of the secondary lymphoid organs
* Site of fetal hematopoiesis, filters blood-borne antigens & cleanses the blood through the action of mononuclear phagocytes, initiates immune responses to blood-borne microbes, destroys aged erythrocytes and serves as a reservoir for blood
Iron Cycle- approx. 67% of total body iron is bound to heme in erythrocytes (hgb) and muscle cells (myoglobin), approx. 30% is stored in mononuclear phagocytes (macrophages) and hepatic parenchymal cells as either ferritin or hemosiderin
* Recycled made possible by the plasma carrier, transferrin
* Tissue macrophage (primarily in the spleen) break down ingested erythrocytes and return iron to the bloodstream directly or after storing it
Hemoglobin Synthesis- oxygen carrying protein of the erythrocyte, constitutes approx. 90% of the cell’s dry weight
* Hgb packed RBCs take up O2 to the lungs and exchange it for CO2 in the tissues
* Single erythrocyte can contain as many as 300 hgb molecules
* Each hgb molecule is composed of 2 pairs of polypeptide chains (the globins) and 4 colorful complexes of iron plus protoporphyrin (the hemes), responsible for blood’s ruby-red color and O2 carrying capacity
* Very dependent on nutritional intake. Two of the most important nutrients are Vitamin B6 (pyridoxine) & Iron
* Male 16g/dL
* Female 14g/dL
Neurophilia- another term for granulocytosis, due to neutrophils being the most numerous of the granulocytes
* Increase in the # of granulocytes (neutrophils, eosinophils, basophils)
* Begins with the release of stored leukocytes from the venous sinuses of the marrow
* Demand mature neutrophils exceeds the supply, marrow begins to release immature neutrophils
* Premature release of the immature WBCs is responsible for the phenomenon known as Shift-to-the-left (Immaturity side). May see other systemic signs of infection such as fever
Anemia
* Reduction in the total circulating red cell mass or a decrease in the quality or quantity of hgb
* Result from blood loss, impaired erythrocyte production, increased erythrocyte destruction or a combination of these factors
* “-cytic” refers to cell size
* “-chromic” refers to hgb content
Type Description
Aplastic Anemia Critical condition, caused by an autoimmune disease against hematopoiesis by activated cytotoxic T-cells
-Characterized by pancytopenia, a reduction or absence of all 3 blood cell types
-Resulting from failure or suppression of bone marrow to produce adequate amounts of erythrocytes, leukocytes, and thrombocytes
Iron Deficiency Can arise with inadequate dietary intake or excessive blood loss
- Most common cause of IDA in developed countries is pregnancy and chronic blood loss
- Early symptoms are nonspecific & include fatigue, weakness, SOB, and pale earlobes, palms, & conjunctivae [Show Less]